Irina Kholodnyuk

A 3p21.3 region is preferentially eliminated from human chromosome 3/mouse microcell hybrids during tumor growth in SCID mice

We have previously shown that four markers spanning the 3p24‐p21.3 region, THRB, AP20R, D3S1029, and D3S32, were regularly eliminated from three human chromosome 3 (chr3)/mouse microcell hybrids (MCHs) during tumor growth in SCID mice. In an attempt to narrow down the eliminated region, we have studied 22 new SCID mouse tumors derived from 5 MCH lines carrying human chr3. They were analyzed by fluorescence in situ hybridization (FISH), Southern blotting, and polymerase chain reaction (PCR). MCHs that carried human chr1, chr8, chr13, and chr17 were examined as controls. We could identify a common eliminated region (CER) at 3p21.3, bordered distally by D3S1260 and proximally by D3S643/D3F15S2. Eight of 53 chr3‐specific PCR markers, AP20R, D3S966, D3S3559, D3S1029, Wl‐7947, D3S2354, AFMb362wb9, and D3S32, were localized within the CER. This finding is consistent with the notion that a tumor suppressor gene may be located in this area, as suggested by frequent loss of heterozygosity (LOH) within this region observed in several types of solid tumors. Genes Chromosom. Cancer 18:200–211, 1997.

Down regulation of 3p genes, LTF, SLC38A3 and DRR1, upon growth of human chromosome 3-mouse fibrosarcoma hybrids in severe combined immunodeficiency mice.

We have applied a functional test for tumour antagonizing genes based on human chromosome 3 (chr3)–mouse fibrosarcoma A9 MCHs that were studied in vitro and after growth as tumours in severe combined immunodeficiency (SCID) mice. Previously, we reported that 9 out of the 36 SCID‐tumours maintained the transferred chr3 (“chr3+” tumours), but lost the expression of the known human TSG fragile histidine triad gene (FHIT) in contrast to 14 other 3p‐genes examined. Here we report the results of the duplex RT‐PCR analysis of 9 “chr3+” tumours and 3 parental MCHs. We have examined the expression of 34 human 3p‐genes from known cancer‐related regions of instability, including 13 genes from CER1 defined by us previously at 3p21.33–p21.31 and 10 genes from the LUCA region at 3p21.31. We have found that in addition to FHIT, expression of the LTF gene from CER1 at 3p21.33‐p21.31 was lost in all 9 tumours analyzed. The transcript of the solute carrier family 38 member 3 gene (SLC38A3) gene from LUCA region at 3p21.31 was not found in 8 and was greatly reduced in 1 out of these 9 tumours. Expression of the down‐regulated in renal cell carcinoma gene (DRR1) gene at 3p14.2 was lost in 7 and down regulated in 2 “chr3+” tumours. In the SCID‐tumour derived cell lines treatment with 5‐aza‐2′‐deoxycytidine restored the mRNA expression of LTF, indicating the integrity of DNA sequences. Notably that transcription of the LTF and 2 flanking genes, LRRC2 and TMEM7, as well as transcription of the SLC38A3 gene, were also impaired in all 5 RCC cell lines analyzed. Our data indicate these genes as putative tumour suppressor genes.

Human/mouse microcell hybrid based elimination test reduces the putative tumor suppressor region at 3p21.3 to 1.6 cM.

We have previously identified an approximately 7 cM long common eliminated region (CER), involving the 3p21.3 markers AP20R, D3S966, D3S3559, D3S1029, WI‐7947, D3S2354, AFMb362wb9, and D3S32, in human chromosome 3/A9 mouse fibrosarcoma microcell hybrid (MCH) derived SCID mouse tumors. We now report the results of our more detailed analysis on 24 SCID mouse tumors derived from two MCH lines that originally carried intact human chromosomes 3. They were analyzed by fluorescence in situ hybridization (FISH) painting and PCR, using 24 markers covering the region between D3S1611 and D3S1235 at 3p22‐p21.2. D3S32 and D3S2354 were regularly eliminated during in vivo tumor growth, whereas the other 22 markers, D3S1611, ACAA, D3S1260, WI‐692, AP20R, D3S3521, D3S966, D3S1029, D3S643, WI‐2420, MST1, GNAI2, D3S1235, D3S1298, GLB1, WI‐4193, D3S3658, D3S3559, D3S3678, WI‐6400, WI‐7947, and WI‐10865, were regularly retained. We have defined a common eliminated region of approximately 1.6 cM (designated as CER1) inside the 7 cM CER described earlier. CER1 is flanked distally by D3S1029 and proximally by D3S643. Genes Chromosomes Cancer 20:329–336, 1997.

Differential elimination of 3p and retention of 3q segments in human/mouse microcell hybrids during tumor growth

We have previously found that human chromosome 3 was fragmented in the course of in vivo tumor growth of monochromosomal human/mouse (A9 fibrosarcoma parent) microcell hybrids in SCID mice. Marker analysis of tumor cell lines has identified a regularly eliminated 7 cM segment on 3p21.3 referred to as the common eliminated region (CER). The same region is frequently affected by LOH in a variety of human carcinomas. The present study is a comparative chromosome painting, reverse painting, and PCR marker analysis of microcell hybrids (MCHs) that originally contained an intact chromosome 3 from two alternative donors, during and after four passages in SCID mice. We found regular elimination of 3p in parallel with preferential retention of 3q. In addition to CER on 3p, we can now define a common retained region (CRR) on 3q. It includes eight markers between D3S1282 (3q25‐q26) and D3S1265 (3q27‐qter) and spans approximately 43 cM. These observations are concordant with the frequent loss of corresponding 3p regions and the frequent retention, with occasional amplification, of 3q in several types of human tumors. Genes Chromosomes Cancer 20:224–233, 1997.

Consistent downregulation of human lactoferrin gene, in the common eliminated region 1 on 3p21.3, following tumor growth in severe combined immunodeficient (SCID) mice

Lactoferrin (LF) is one of 19 active genes in the common eliminated region 1 at 3p21.3 identified by us. LF was transfected into mouse fibrosarcoma A9. Fourteen severe combined immunodeficient (SCID) derived tumors from two PI based artificial chromosome (PAC)-transfectants containing the entire LF gene and two LF-cDNA transfectants were analyzed by real time polymerase chain reaction at the DNA and RNA level. Following SCID tumor passage, LF expression was decreased or eclipsed, in all tumors although DNA levels did not change considerably. Promoter methylation and/or rearrangement of the insertion site may be responsible for human LF downregulation in mouse fibrosarcoma derived tumors.

The microcell hybrid-based “elimination test” identifies a 1-Mb putative tumor-suppressor region at 3p22.2–p22.1 centromeric to the homozygous deletion region detected in lung cancer

We have previously shown that inoculation of human chromosome 3 (chr3)/A9 mouse fibrosarcoma microcell hybrids (MCHs) into severely combined immunodeficient (SCID) mice was followed by the regular elimination of certain 3p regions, whereas a 3q region was retained even after prolonged mouse passage. Using this approach, referred to as the elimination test (Et), we identified a common eliminated region (CER) of about 7 cM at 3p22–p21.3 that was absent in all tumors generated from five MCHs. A second frequently eliminated region (FER, originally called ER2) was found at 3p21.1–p14.2. These segments have been reported to be frequently deleted in a variety of carcinomas. In the following experiments, we have identified at the centromeric border of CER a common eliminated region 1 (CER1) of about 1.6 cM. We now report the results of more detailed analyses of the original tumor panel that contained 30 SCID mouse tumors. Using polymerase chain reaction and chromosome reverse painting, we have identified at the telomeric border of CER a second common eliminated region (designated as CER2). CER2 is flanked distally by RH94338 and proximally by SHGC‐154057. The size of CER2 is about 1 Mb, according to the Homo Sapiens Complete Genome databases at EMBL, and is located about 0.5 Mb centromeric to the known homozygous deletion region, identified in lung cancer. Remarkably, two chemokine‐receptor genes (CCRs), CCR8 and CX3CR1, are located within CER2, whereas seven CCRs were found within CER1.

Mandatory chromosomal segment balance in aneuploid tumor cells

BackgroundEuploid chromosome balance is vitally important for normal development, but is profoundly changed in many tumors. Is each tumor dependent on its own structurally and numerically changed chromosome complement that has evolved during its development and progression?We have previously shown that normal chromosome 3 transfer into the KH39 renal cell carcinoma line and into the Hone1 nasopharyngeal carcinoma line inhibited their tumorigenicity. The aim of the present study was to distinguish between a qualitative and a quantitative model of this suppression. According to the former, a damaged or deleted tumor suppressor gene would be restored by the transfer of a normal chromosome. If so, suppression would be released only when the corresponding sequences of the exogenous normal chromosome are lost or inactivated. According to the alternative quantitative model, the tumor cell would not tolerate an increased dosage of the relevant gene or segment. If so, either a normal cell derived, or, a tumor derived endogenous segment could be lost.MethodsFluorescence in Situ Hybridization based methods, as well as analysis of polymorphic microsatellite markers were used to follow chromosome 3 constitution changes in monochromosomal hybrids.ResultsIn both tumor lines with introduced supernumerary chromosomes 3, the copy number of 3p21 or the entire 3p tended to fall back to the original level during both in vitro and in vivo growth. An exogenous, normal cell derived, or an endogenous, tumor derived, chromosome segment was lost with similar probability. Identification of the lost versus retained segments showed that the intolerance for increased copy number was particularly strong for 3p14-p21, and weaker for other 3p regions. Gains in copy number were, on the other hand, well tolerated in the long arm and particularly the 3q26-q27 region.ConclusionThe inability of the cell to tolerate an experimentally imposed gain in 3p14-p21 in contrast to the well tolerated gain in 3q26-q27 is consistent with the fact that the former is often deleted in human tumors, whereas the latter is frequently amplified. The findings emphasize the importance of even minor changes in copy number in seemingly unbalanced aneuploid tumors.

Expression of the chemokine receptors CCR1 and CCR2B is up-regulated in peripheral blood B cells upon EBV infection and in established lymphoblastoid cell lines

In immunocompetent individuals, EBV establishes in B cells an asymptomatic lifelong latent infection controlled by the immune system. Chemokine receptors regulate immune system function. CCR1 and CCR2 share protein sequence similarity and exert responses to multiple chemokines. The role of these receptors in B cells is largely unknown. We show that the mRNA and functional protein expression of CCR1 and CCR2 is induced in ex vivo B cells upon EBV infection and in established lymphoblastoid cell lines (LCLs). The CCR1 and CCR2B ORF transcripts were determined in LCLs. In contrast, in both the EBV-negative and EBV-positive Burkitt lymphoma cell lines, neither the CCR1, CCR2A, and CCR2B ORF transcripts nor their corresponding proteins were detected. Our data suggest that CCR1/CCR2B could be involved in clearing EBV-infected latency III B cells in immunocompetent individuals via directing the migration of these cells and attracting the chemokines-expressing immune cells.

Upregulation of the Chemokine Receptor CCR2B in Epstein‒Barr Virus-Positive Burkitt Lymphoma Cell Lines with the Latency III Program

CCR2 is the cognate receptor to the chemokine CCL2. CCR2–CCL2 signaling mediates cancer progression and metastasis dissemination. However, the role of CCR2–CCL2 signaling in pathogenesis of B-cell malignancies is not clear. Previously, we showed that CCR2B was upregulated in ex vivo peripheral blood B cells upon Epstein‒Barr virus (EBV) infection and in established lymphoblastoid cell lines with the EBV latency III program. EBV latency III is associated with B-cell lymphomas in immunosuppressed patients. The majority of EBV-positive Burkitt lymphoma (BL) tumors are characterized by latency I, but the BL cell lines drift towards latency III during in vitro culture. In this study, the CCR2A and CCR2B expression was assessed in the isogenic EBV-positive BL cell lines with latency I and III using RT-PCR, immunoblotting, and immunostaining analyses. We found that CCR2B is upregulated in the EBV-positive BL cells with latency III. Consequently, we detected the migration of latency III cells toward CCL2. Notably, the G190A mutation, corresponding to SNP CCR2-V64I, was found in one latency III cell line with a reduced migratory response to CCL2. The upregulation of CCR2B may contribute to the enhanced migration of malignant B cells into CCL2-rich compartments.

Molecular Mapping of the Human 3p Region

The aim of this study is to identify the gene(s) on the short arm of human chromosome 3, the loss of which contributes to the occurrence of kidney carcinoma and other solid tumors. The critical role of aberrations detected on the short arm of chromosome 3 have been suggested by recent cytogenetic and molecular studies with restriction fragment length polymorphism in relation to the development of renal cell carcinoma [6, 7], von Hippel Lindau disease [13], lung cancer [9], and breast cancer [3]. The majority of the RCC tumors can be characterized cytogenetically by deletions of the short arm of chromosome 3 from 3pl3 to 3pter [7]. Restriction fragment length polymorphism analysis of tumor-derived DNA have revealed allelic losses of known polymorphic DNA markers localized to various parts of 3p, suggesting the involvement of a tumor suppressor gene, probably near the D3F15S2 marker (3p21), in the origin and/or evolution of renal cell carcinoma [6]. The search for a tumor suppressor gene in the affected region, however, is hampered by the size of the chromosomal segment involved (minimal estimation is 40 Mbp) along the approximately 100 Mbp sized short arm of chromosome 3 [8]. Large areas exist from which no unique sequences are available.